Tubers were spread from New Zealand to Hawaii before European contact.

The sweet potato was one of a number of crops domesticated in the Andes and, like many of the rest, it became a global crop in the colonial era. But there were some hints that the sweet potato may have already started its global sweep before the Europeans ever took a bite out of one. Some of the early European explorers, including Captain Cook, reported finding it in places like Hawaii. All of which implies that the Polynesians, who managed to spread widely across the Pacific, had made it all the way to South America.

But it was difficult to be sure, given that European travelers later enhanced its spread within the Pacific and elsewhere. This has also created a complex genetic legacy that obscures its origins. Now, researchers have gone back and obtained DNA from museum samples, including some collected by Cook's crew, and find that the DNA indicates that Polynesians made it as far as South America.

Archeological remains appear to place sweet potato cultivation in the core of Polynesia by the year 1200, and it spread with further migrations to places like New Zealand and Hawaii. It's possible that the plant had naturally spread as seeds across the ocean and the Polynesians learned to cultivate it independently. One of the arguments against this is the fact that the Polynesian terms for the crop appear to be closely related to its name in Quechua, the language of the Peruvian Andes. ("Kuumala" and derivatives vs. "kumara" and relatives.)

That, and the fact that the Polynesians made it most of the way across the Pacific, clearly getting as far as Easter Island. Still, reaching South America and then returning with crops is quite a significant step beyond that.

Trying to piece together a model of the sweet potato's spread based on things like historical reports, known human travels, and genetic information, however, has been quite a mess. Even the simplest ideas that are consistent with the data involve the sweet potato entering the Pacific through three different routes, and then potentially hybridizing with the strains already in residence.

It may be complicated, but the new genetic study provides support for this three-pronged (tripartite) assault on the Pacific. The researchers start with a detailed study of the cultivars found in South America, Central America, and the Caribbean. The researcher team, based in France, found that there are two distinct populations: a northern strain, found in Mexico and the Caribbean, and a southern one, in the Andes, where the crop was first domesticated. (There's also a region of overlap and intermingling in between the two.)

Genetic relatives of the northern strain entered the Pacific via two routes. In the first, trade with the Philippines during the Spanish colonial era brought it there; from that site, it diffused into mainland Asia and to some island strains. But the Caribbean strain made its way across the Atlantic, through Madagascar, and into Indonesia. Its arrival, likely in the 1700s, transformed the agriculture of the New Guinea highlands, which had previously been focused on taro. Cultural changes followed in its wake.

Most modern cultivars are descended from some combination of these two invasions. But samples from museums, including some collected by the earliest European voyagers, show that this wasn't likely to be the case prior to the late 1800s. Before then, most strains were spread directly from initial sources, with very little interbreeding.

The other thing that museum samples indicate is that, prior to extensive European travels in the Pacific, there was another, genetically distinct form of the sweet potato present in Eastern Polynesia. And that appears to have originated from the southern population, focused in the Andes. It was already present in Polynesia before colonists left this region to settle in Hawaii and New Zealand.

Given that we already know Polynesians had the technology to engage in long-distance voyages across the Pacific, the simplest explanation for this is that they did make it to South America, probably somewhere around the year 1000. And, most strikingly, some of them apparently turned around and traveled back halfway across the Pacific.

This, combined with last week's results that showed travelers from India made it to Australia over 4,000 years ago, provides impressive evidence of just how mobile some of our ancestors have been. And they managed to travel all that distance with technologies we'd generally consider primitive. But it's important to consider that, just because you wouldn't hop into an open canoe and head out into the Pacific, it wouldn't have meant certain death for anyone with the right skills.

Promoted Comments

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast. It doesn't matter how big a raft you have, you will lose a lot of them.

Again with the rafts. They didn't use rafts, get that Kon-Tiki fantasy out of your head. They used double hulled voyaging canoes that were large and quite fast (for something reliant on sails). They used stars and trade winds to navigate and also seabirds as methods to detect land. I'm not saying nobody ever died doing this, just that is wasn't as random as you're thinking.

"samoanbiscuit"]While most people think of tiny sunny atolls when they think of Polynesia, the larger island groups (Fiji, Hawaii, Samoa and Tonga) have always supported large populations.

Those big islands are all on the west side of the very big region we are discussing. Except for Hawaii, which is well to the north (and one of the last to be settled). There's a lot of small-island hopping to do if you start at Fiji and end at South America.

samoanbiscuit wrote:

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast, rafts too dangerous and the navigation techniques too limited. It doesn't matter how big a raft you have, you will lose a lot of them if you're sailing around the South Pacific looking for atolls.

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast. It doesn't matter how big a raft you have, you will lose a lot of them.

Again with the rafts. They didn't use rafts, get that Kon-Tiki fantasy out of your head. They used double hulled voyaging canoes that were large and quite fast (for something reliant on sails). They used stars and trade winds to navigate and also seabirds as methods to detect land. I'm not saying nobody ever died doing this, just that is wasn't as random as you're thinking.

Traveling long distances is difficult but can be mastered if you know a few tricks.European sailors of the 15th century were hampered by their need of keeping everything they eat & drink during the journey with them.Ancient sailors could rely on fish from the sea and water collected during rain. So they could travel much longer distances. Navigating done by heavenly objects and the swell can obviously get a sailor pretty accurate to where he wants.While you can discover a continent by chance (as Columbus did), when traveling back home a sailor definitely has to navigate very accurate to find his home island.

Careful. The open ocean can be very difficult to forage in. Especially on a raft with little maneuverability. There aren't huge schools of fish everywhere. (Parts of the South Pacific have been compared to deserts in that way.)

You really have to discriminate, also, between long trips of exploration and trade trips to known locations. Much of polynesian trading would have been done by travelling along archipelagos. When traveling between archipelagos, you could miss one island and pass close enough to another so you could figure out where you are -- "oh, I must have missed Tahiti, because there's Bora Bora". this is a very different issue than getting to/from Easter Island -- which really sits out there by itself.

Furthermore, if the travel was very easy, you wouldn't see loss of technology and food species as you travel east. Inter-archipelago trading was clearly more limited than intra-archipelago trading.

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast. It doesn't matter how big a raft you have, you will lose a lot of them.

Again with the rafts. They didn't use rafts, get that Kon-Tiki fantasy out of your head. They used double hulled voyaging canoes that were large and quite fast (for something reliant on sails). They used stars and trade winds to navigate and also seabirds as methods to detect land. I'm not saying nobody ever died doing this, just that is wasn't as random as you're thinking.

How do you explore without randomness? You can only follow seabirds visually to the horizon. The methods to detect land over the horizon (birds headed "that way", cloud formations static over land, etc.) only get you so far. At some point, you've got to just decide to try heading that way. And if there's a big storm when you're all the way "that way", you might not be able to find your way back. Especially over the big separations. You can explore an archipelago by the process of "go that way for a week, if you don't find anything, turn around and come directly back". That doesn't get you to Easter Island very easily. Also doesn't get you up to Hawaii.

And why do you pack your whole family on a big canoe without population pressure behind you? Just for a romantic voyage? Unlikely.

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast. It doesn't matter how big a raft you have, you will lose a lot of them.

Again with the rafts. They didn't use rafts, get that Kon-Tiki fantasy out of your head. They used double hulled voyaging canoes that were large and quite fast (for something reliant on sails). They used stars and trade winds to navigate and also seabirds as methods to detect land. I'm not saying nobody ever died doing this, just that is wasn't as random as you're thinking.

How do you explore without randomness? You can only follow seabirds visually to the horizon. The methods to detect land over the horizon (birds headed "that way", cloud formations static over land, etc.) only get you so far. At some point, you've got to just decide to try heading that way. And if there's a big storm when you're all the way "that way", you might not be able to find your way back. Especially over the big separations. You can explore an archipelago by the process of "go that way for a week, if you don't find anything, turn around and come directly back". That doesn't get you to Easter Island very easily. Also doesn't get you up to Hawaii.

And why do you pack your whole family on a big canoe without population pressure behind you? Just for a romantic voyage? Unlikely.

The reasons behind the polynesian expansion are not clear. Maybe religious, maybe political, maybe population pressure, and sometimes maybe a storm blew some people in the wrong direction; probably all these reasons and more. It's also well accepted that when reaching a new archipelago, they preferred to settle the smaller islands first (at least in Western Polynesia). The technique I refer to when I mentioned using seabirds to detect land is the use of frigate birds. These don't land on water, so if one is released and does not return to the canoe in a day or so, then an island was probably nearby.There was a definite separation between western polynesia, eastern polynesia and new zealand, but within these zones (which are substantial in their own right) there was considerable contact, usually (in the west) involving raids or even invasion. The more stratified and warlike a society was, the more incentive for warriors to search for smaller outliers to raid. When european explorers reached western polynesia, they arrived during a period of political unrest where a Tongan king had commanded Samoan canoe builders to use Fijian timber to build the largest war canoes yet found in the Pacific (some more than 100ft long). These were then used to subjugate a large part of the islands in what is now south-eastern Fiji (the Lau group). Smaller western islands all have oral accounts of invasions by Samoan and Tongan raiding parties often staying for years, which is granted some credence by the large amounts of tongan and samoan loan words found in their language.

"samoanbiscuit"]While most people think of tiny sunny atolls when they think of Polynesia, the larger island groups (Fiji, Hawaii, Samoa and Tonga) have always supported large populations.

Those big islands are all on the west side of the very big region we are discussing. Except for Hawaii, which is well to the north (and one of the last to be settled). There's a lot of small-island hopping to do if you start at Fiji and end at South America.

samoanbiscuit wrote:

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast, rafts too dangerous and the navigation techniques too limited. It doesn't matter how big a raft you have, you will lose a lot of them if you're sailing around the South Pacific looking for atolls.

The Polynesian sailors did not need to use visual sightings. They navigated by current, wave pattern, debris and bird flight when exploring. For known destinations they also used star charts. Unlike modern sailors, these traditional navigators can read the seascape for clues to land masses that are over the horizon. This was (and is) a highly trained skill that is usually handled by specialists who guide the expedition.http://www.passengerplanet.com/softwarm.html

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast. It doesn't matter how big a raft you have, you will lose a lot of them.

Again with the rafts. They didn't use rafts, get that Kon-Tiki fantasy out of your head. They used double hulled voyaging canoes that were large and quite fast (for something reliant on sails). They used stars and trade winds to navigate and also seabirds as methods to detect land. I'm not saying nobody ever died doing this, just that is wasn't as random as you're thinking.

The Polynesian sailors did not need to use visual sightings. They navigated by current, wave pattern, debris and bird flight when exploring. For known destinations they also used star charts. Unlike modern sailors, these traditional navigators can read the seascape for clues to land masses that are over the horizon. This was (and is) a highly trained skill that is usually handled by specialists who guide the expedition.http://www.passengerplanet.com/softwarm.html

Thankyou for this post and link! This is what I was trying to get at earlier. Their traditional navigators can "see" land masses in the wave/swell patterns. This is born of millenia of seafaring using traditional methods. They're not travelling blind at all.

The Polynesian sailors did not need to use visual sightings. They navigated by current, wave pattern, debris and bird flight when exploring. For known destinations they also used star charts. Unlike modern sailors, these traditional navigators can read the seascape for clues to land masses that are over the horizon. This was (and is) a highly trained skill that is usually handled by specialists who guide the expedition.http://www.passengerplanet.com/softwarm.html

Thankyou for this post and link! This is what I was trying to get at earlier. Their traditional navigators can "see" land masses in the wave/swell patterns. This is born of millenia of seafaring using traditional methods. They're not travelling blind at all.

That page mostly relates short-range (just over the horizon) sighting systems mixed in with a few examples of pure hocus-pocus. And even the short-range systems will only be effective under certain atmospheric conditions. Perhaps that is why Hawaii and New Zealand were both found basically last among all the Polynesian islands. In spite of being the biggest land masses settled exclusively by Polynesians, they are really far from the other islands, so don't lend themselves to being found by just-over-the-horizon methods.

... there was much less randomness to the voyaging than what Thor Heyerdahl and the rest would have you believe.

That's simply impossible. There's too much water and not enough land for it to be anything but a crap shoot. Follow-up trading would have been much less dangerous, but the initial discovery of the next island chain? The distances in the South Pacific are simply too vast. It doesn't matter how big a raft you have, you will lose a lot of them.

Again with the rafts. They didn't use rafts, get that Kon-Tiki fantasy out of your head. They used double hulled voyaging canoes that were large and quite fast (for something reliant on sails). They used stars and trade winds to navigate and also seabirds as methods to detect land. I'm not saying nobody ever died doing this, just that is wasn't as random as you're thinking.

Oh, you're right. Sail cats change the whole analysis. Must have been a walk in the park for those Polynesians.

Hopefully you're sensing the sarcasm.

If the exploration process were so safe and straightfoward, why did it take a thousand years or so for them to settle the whole way across?

I've never denied they got to those places. I'm just saying that the romantic ideal of the seafaring Polynesians as master explorers (as opposed to merely very knowledgeable seafarers) belies the combination of known facts and human nature.

Fact: It took a long time to settle all of what is now known as Polynesia. Master explorers capable of very-long-range sea travel at low risk would not have taken 20-30 generations to find all of those islands.

Fact: Trade goods (food species and technologies) did not transfer evenly throughout Polynesia. And the distribution reflects loss of species/technologies with distance from the origin, rather than selection based on local conditions. Long distance travel between archipelagos must, therefore, have been relatively rare.

Fact: Settled people with no population pressure are unlikely to up and move whole families hundreds of miles to newly discovered islands. This is just human nature. Furthermore, small populations limited to small geographies are at greater risk for cycles of feast and famine. It's easy to imagine a small atoll becoming overcrowded after a period of plenty and the elders deciding to send off some settlers to reduce population pressure. Whether those settlers had a whole lot of say in the matter or even had a particular destination in mind would be key questions.

So, all I was saying was this: I do not believe the Polynesians were master explorers regularly going out on multi-week or multi-month exploration expeditions with relatively low risk. While they were certainly excellent seafarers, with lots of tricks for navigating well away from landmarks, I believe the Polynesians' long-range explorations were highly risky, often driven by desperation and luck played a big factor in who made it to land and who died at sea.

The Polynesian sailors did not need to use visual sightings. They navigated by current, wave pattern, debris and bird flight when exploring. For known destinations they also used star charts. Unlike modern sailors, these traditional navigators can read the seascape for clues to land masses that are over the horizon. This was (and is) a highly trained skill that is usually handled by specialists who guide the expedition.http://www.passengerplanet.com/softwarm.html

Thankyou for this post and link! This is what I was trying to get at earlier. Their traditional navigators can "see" land masses in the wave/swell patterns. This is born of millenia of seafaring using traditional methods. They're not travelling blind at all.

That page mostly relates short-range (just over the horizon) sighting systems mixed in with a few examples of pure hocus-pocus. And even the short-range systems will only be effective under certain atmospheric conditions. Perhaps that is why Hawaii and New Zealand were both found basically last among all the Polynesian islands. In spite of being the biggest land masses settled exclusively by Polynesians, they are really far from the other islands, so don't lend themselves to being found by just-over-the-horizon methods.

If you look at the ocean currents you find these islands quickly. Just because european sailing vessels were more dependant on erratic sea breezes, does not mean your observation of sailing methods is true.

The Polynesian sailors did not need to use visual sightings. They navigated by current, wave pattern, debris and bird flight when exploring. For known destinations they also used star charts. Unlike modern sailors, these traditional navigators can read the seascape for clues to land masses that are over the horizon. This was (and is) a highly trained skill that is usually handled by specialists who guide the expedition.http://www.passengerplanet.com/softwarm.html

Thankyou for this post and link! This is what I was trying to get at earlier. Their traditional navigators can "see" land masses in the wave/swell patterns. This is born of millenia of seafaring using traditional methods. They're not travelling blind at all.

That page mostly relates short-range (just over the horizon) sighting systems mixed in with a few examples of pure hocus-pocus. And even the short-range systems will only be effective under certain atmospheric conditions. Perhaps that is why Hawaii and New Zealand were both found basically last among all the Polynesian islands. In spite of being the biggest land masses settled exclusively by Polynesians, they are really far from the other islands, so don't lend themselves to being found by just-over-the-horizon methods.

If you look at the ocean currents you find these islands quickly. Just because european sailing vessels were more dependant on erratic sea breezes, does not mean your observation of sailing methods is true.